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<H1>in_chrstore(+CHRConst)</H1>
Test if CHRConst is in the CHR constraint store or not
<DL>
<DT><EM>CHRConst</EM></DT>
<DD>A CHR constraint
</DD>
</DL>
<H2>Description</H2>
  This predicate is used to test if a particular CHR constraint is in the
  CHR constraint store or not. It can be used to prevent the addition of
  redundant constraints. This only useful if the 'already_in_store' 
  option is off. 

<H3>Modules</H3>
This predicate is sensitive to its module context (tool predicate, see @/2).
<H2>Examples</H2>
<PRE>    X leq Y, Y leq Z ==&gt; \+in_chrstore(X leq Z)| X leq Z.
</PRE>

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